brucej

Try holding the clutch in for 10 seconds or so with the bike in neutral before putting it in gear; that should let the discs get loosened up so it won't take off on you. An oil change may help. Going by memory, it takes about 700mls of fluid. There is a sight glass to check the level, just hold the bike straight up and check that it is about half way up the glass. The sight glass is also the filler hole, BTW. There are many different opinions about what kind of oil to use, maybe you could check with the previous owner to see what's in it now and use the same since it works well after the first bit. Hope this helps, Bruce

The street legal TY250S monos had more padding than the R models. You could try at a Yam dealer or at a breaker if you're in the UK.

Best way I found was to take the shock off the bike, then with one end of the shock held in a vise, loosen the lock ring and turn the adjusting ring with a pipe wrench. I helped a friend adjust his on the bike by using a long pry bar to push up on the spring, taking the spring pressure off the rings, then using a punch to turn them, but it is easy to slip and gouge up the bike and was awkward to do.

I don't think resurfacing the fork tubes is a good idea. These tubes have a low friction coating on them ( which gives them the black colour ). Attacking them with emery will do nothing good.

When you adjust the lever, pull the rubber dust cap back so you can see the piston inside the master cylinder. The lever should be adjusted so that the piston comes all the way back and rests against the snap ring that holds it in the cylinder, when the lever is let out. Adjusting the lever to get the least amount of freeplay that allows the piston to come all the way back, will give you the least amount of clutch drag. Lighter oil will give you less clutch drag. Dexron ATF will give you noticeably less drag than 5W-30, but some people say it isn't as good a lubricant for the transmission. After the clutch plates are out, you can check for grooves on the outer basket without removing it. You would need a clutch holding tool, torque wrench, and propper torque spec to remove and re-install it. You will likely always have some amount of drag in your clutch, but it shouldn't be so much that it causes problems when you are riding. Cheers, Bruce

I bet that made for a few interesting moments! Could be a sheared flywheel key. I would check it out before trying to start it again. Cheers, Bruce

The mid muffler does have packing in it, but unfortunately is not built to be re-packed. It is possible for a skilled welder to cut it apart, replace the packing, and weld it back together. I think most people just try to give the bike a good hard run once in a while to clean it out, if they worry about it at all. It's hard to say if yours is clogged up or not, I just thought it might be a possibility. Bruce

Hi Crash, yes it's a floating disc. You might want to check that the mounting bolts are properly snugged up, they have been known to loosen and back out. Good luck with your new bike Bruce

Hi Jeff, did you clean or replace the mid muffler or is it just the end silencer that's new? Another method to soften power delivery is to retard timing. Bruce

Thanks for the reply, Charlie. No doubt a good tuner would be able to sort it out without much trouble. That would be the easy way to fix it. It wouldn't satisfy my curiousity much, though. Having a good tuner explain to me what they do and why they would do it would be much better. I'll try and restate my question to make it clearer what I'm looking for: Milling the head, or removing the gasket, does two things to the combustion chamber - it reduces the squish clearance and it raises compression. These are separate factors, even though they are changed by one operation. General knowledge (by that I mean for engines in general and not for the TY in particular) states that reducing squish clearance will lessen detonation. General knowledge also states that increasing compression will worsen detonation. So, when the TY is modified by milling the head or removing the head gasket, is some of the benefit of the reduced squish clearance being cancelled out by the raised compression? If it is, that presents an opportunity. It is possible, and shoudn't even be very hard, to reduce squish clearance in the TY head without raising compression. All it would take is an additional machining operation to remove some material in the deep part of the combustion chamber, away from the squish band. This operation would restore chamber volume (and therefore compression) back to what it was before the squish clearance was reduced, and so allow the full benefits of the reduced squish clearance to be gained. This idea sounds reasonable to me, but I'm very much aware that my experience with this stuff is limited, so what I'm hoping for is some feedback on it. I could just go ahead and try it, but it would be nice to know if anyone else has tried something along these lines before carving up my head. Bruce Marky G, I didn't mean to snub you, I just took too long putting this together - you hadn't posted yet when I started. I'm curious to know if you have done anything to your bikes to help the problem or just never had a problem to start with? I do think that with good enough gasoline it would never be a concern. :hat:

I think milling the head, or removing the head gasket, to reduce pinging is a really interesting solution to this problem. It's interesting because it is the opposite of the advice often given for other engines - which is to lower compression to reduce pinging. My understanding is that lowering compression reduces pinging in many engines because it lowers the temperature in the combustion chamber, preventing end gases or hot spots from getting hot enough to self-ignite. I can't say that I completely understand why reducing the squish clearance makes the TY run better (better heat transfer from piston to head, or less fuel trapped at the outer edges of the cylinder, maybe?), but I have heard it from enough people that should know to accept it. Maybe someone with better technical knowledge than me could comment on that? My own bike has had the head milled, reducing the squish clearance from .080" to .065", and it seemed to help slightly but not cure the problem. Taking more off might work better. So what I'm wondering is this: Is reducing squish clearance in these bikes less effective than it could be because it is raising the compression, and thereby increasing the heat produced in the chamber? It shoudn't be terribly hard to mill the head to bring the squish clearance down to where it should be, and then take some material off the inside of the chamber to bring chamber volume back to stock, or maybe even larger. Has anyone tried something along these lines, or have any comments about why it should or shouldn't work? -Bruce PS Jalewood, I hope I'm not hi-jacking this thread, making it more theoretical than perhaps you were looking for. I could move it to a new thread if you want me to, just let me know. :hat:

Jalewood, the recommended plug on my 84 250 is a BR6ES NGK, I would imagine your 85 should use the same or similar. Changing the plug won't likely help your problem, though. Detonation is common on the 250s, just like it is on the 350s, for the same reasons - so kevin j's cures will work on your bike, too. Higher octane fuel helped my bike a lot, I would recommend trying that to start, then seeing if you think you need to do something more. Cheers, Bruce

Yes, I am aware that the Husqvarna was the original design. My post doesn't really say which was first, I assumed most people would know. Thankyou for clarifying things P.S. The original subject here was F.I. vs. carb., my post is not the first hijack here!

Regarding other bikes that have not used an oil pump in a 4t engine: the 1980's Husqvarna 4t engines were also like this. Probably they were designed by the same people as did the Husaberg. I remember reading at the time, that this was common in speedway bikes, though I can't verify that fact.

Pretty sure he means the inner race, Charlie. Just like you described in your post.